WROUGHT IRON. 91 plicate the relation between the chemical composition and the physical properties, and it need not be wondered that the committee could not find the exact influence of each chemical component. TABLE III-D. Variations in Specimens Submitted to the United States Board for Testing Chain Cables. Subject. Same Iron All Irons. Min. Max. Min. Max. Carbon, per cent., .026 .042 .064 .512 .015 .612 Phosphorus, per cent., .065 .095 .232 .250 .005 .817 Silicon, per cent., .028 .182 .182 .821 .028 .821 Manganese, per cent., tr. .021 .059 .097 tr. .097 Slag, per cent., 0.674 1.248 1.788 2.262 , 0.192 2.2G2 Ultimate strength, pounds per square inch, 56201 47478 69779 57867 47478 69779 Elongation in 8 inches, per cent., 11.7 14.1 20.6 82.5 6.5 82.7 Beduction of area, per cent., 27.7 16.0 59.8 81.5 7.7 69.8 There was formulated, however, the following valuable conclusion: "Although most of the irons under consideration are much alike in composition, the hardening effects of phosphorus and silicon can be traced, and that of carbon is obvious. Phosphorus up to .20 per cent, does not harm and probably improves irons containing silicon not above .15 per cent, and carbon not above .03 per cent. None of the ingredients, except carbon in the proportions present, seem to very notably affect the welding by ordinary methods/3 Regarding this last clause it should be said that the highest sulphur in any sample was .015 per cent., which is low; but copper was present up to .43 per cent.; nickel up to .34 per cent., and cobalt up to .11 per cent. Moreover, the high percentages of these three elements were coincident in one bar, yet welding gave fair results, notwithstanding that phosphorus was higher than was advisable. The experiments were far from conclusive as to these elements.